Draft-gage.



Patented Apr. 22, I902.

K. BOMHARD.

DRAFT GAGE.

(Application filed Heb. 26, 1901.)

(No Modei.)

lUbfiLesses.

Attorney.

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- UTTED STATES PATENT OFFICE.

KARL BOMl-IARD, OF AIX-LA-CHAPELLE, GERMANY.

DRAFT-GAG E.

SPECIFICATION forming part of Letters Patent No. 697,970, dated April 22, 1902.

" Application filed February 26, 1901. Serial No. 48,991. (Nomodeh) To all whom it may concern:

Be it known that I, KARL BoMHARD, engineer, a subject of the King of Prussia, Emperor of Germany, residing at 99 Friedrichstrasse, Aix-laChapelle, in the Kingdom of Prussia, Empire of Germany, have invented certain new and useful Improvements in Draft-Gages; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My present invention relates to draft-gages; and the object in view is to provide a simple yet very effective instrument which has neither springs, valves, nor any other devices which might become clogged, nor is it infiuenced by the changes in temperature, for

which reason it is especially adapted for boiler plants and similar heating means. The degree of draft existing in any part of lines or chimneys is clearly indicated by a pointer upon a scale, but returns to its original position as soon as it is out of use. As the instrumentis of the simplest construction possible, it can be very cheaply manufactured and will hardly ever need any repairs.

The accompanying drawing shows the draft-gage partly in section.

The under side of the receptacle C6 is provided with a short nipple b and the inside of the same receptacle with a pipe 0. The re ceptacle is filled to about half its depth with a liquid cl, preferably glycerin, into which dips the double-walled bell e, kept central by the guides g. The cover it of the bell e is provided with a rack i, guided in brackets 7t, fastened to the back wall of the housing Z, which at its lower end surrounds the upper part of the receptacle a and is kept in place thereon by means of the little screws m. At the center of the housing is also secured a short spindle 72, upon which are movably secured the piniono, meshing with the rack i, and the pointer 19, playing upon a scale f on the face of said housing.

In operation the nipple b is inserted in a rubber tube and the free end of the latter fastened to the end of a pipe communicating with the interior of a fine or chimney wherein the draft is to be measured. This may, however, be arranged in any other desirable manner. As soon asthe connection is made the draft-gage is ready for work, as no cocks or valves are contained therein. The draft existing in the flue, chimney, &c., will draw air out of the interior of the bell e, establish a partial vacuum therein, and cause the latter to sinkin direct proportion to theintensity of the draft until equilibrium between the atmosphere and pressure within the bell is established. It is clear that a difference in the intensity of the draft will cause the bell to assume different positions in reference to a given point of the receptacle a and in consequence will rotate the pointer 19 more or less by means of its connection with the latter. The pointer shows at a glance the degree of the existing draft upon the scale f, but returns to its startingpoint as soon as the atmospheric pressure gains access to the interior of the floating bell.

I claim- 1. A draft-gage comprising a receptacle with a central tube, a double-walled, vertically-guided and vertically freely moving bell provided with a chamber for the reception of the upper mouth of said central tube; a housing secured to said receptacle; a pinion revolubly secured to said housing; a rack secured to the top of said bell for transmitting the vertical motion of it to said pinion; and a pointer carried by said pinion to make the vertical motion of said double-walled bell visible upon a scale.

2. In a draft-gage as described the combination of a receptacle having a central tube and containing a sealing liquid with a doublewalled vertically-moving bell containing a chamber normally surrounding the upper mouth of said tube; a housing secured to said receptacle; a pinion revolubly secured to said housing and carrying a pointer to visibly indicate upon a scale the vertical motion of said double-walled bell; a rack secured to the top of said bell and meshing with said pinion and means for guiding said bell and the rack, substantially as specified.

In testimony that I claim the foregoing as my invention I have signed my name in presence of two subscribing witnesses.

KARL BOMHARD.

Witnesses:

O. E. BRUNDAGE, I-I. QUADFLIEG. 

